Adventures Among Ants - Mark W. Moffett [124]
In its early stages, a colony undergoes a kind of embryonic development at a superorganism level.81 By the time the queen’s initial brood is old enough to leave the nest, the young society seems as precocious as a calf, with its wobbly ability to stand at birth. The queen’s first twenty to sixty workers encompass a minimum range of middling worker sizes needed to form a simplified version of the processing line of mature colonies, just enough to tend the garden and the young and to cut and process leaves, and thereby get the colony going. In the months that follow, it will grow in complexity as smaller and larger ants appear.82
With luck, the queen found a nesting spot in an open habitat. Even the recent death of one tree within a forest may provide a good-enough start. A tall tree rends a hole in the canopy when it collapses. This treefall gap lets light into the understory, allowing herbs and pioneer trees, which do poorly in deep forest shade, to move in. Even a juvenile colony’s modest labor force can process saplings of these plants, whose soft foliage is easily cut by small, less powerful workers.83 During its first, exploratory years, a colony creates temporary trails straight to such small plants within a short distance of the nest.
A growing colony will add larger road-building and leaf-cutting workers as it expands its reach to the canopy. This is to be expected: work tends to be divvied up in large societies (and in the bodies of large organisms) as a result of the differing functions or duties that must be performed in the larger, more variable area they occupy; the first complex human cultures, for example, arose where populations were dense enough for trading to become practical, and local groups could develop and maintain particular skills involving goods, such as flints for tools, specific to where they lived.84
When the larger leaf-cutting workers begin to appear, they first test their mettle on tougher tree foliage that has fallen to the ground. Finally the colony begins to build its first durable trunk trails, which never lead directly to single bonanza plants like the colony’s first feeble trails did, and the workers start to climb tall trees. It takes a couple years to add soldiers to the mix. By this time workers have begun harvesting in the high canopy and carving out giant midden chambers well before they are needed—which will be long after the crews that built them are dead, because the workers live only a few weeks.85 By its fifth year the superorganism has reached sexual maturity, producing males and queens that depart on mating flights. The superorganism can survive twenty-five years, it appears: that’s the record life span for a leafcutter queen, and there are no backups.
15 the origins of agriculture
In Ecuador I once had the good fortune to sit in view of the Napo, an immense tributary of the Amazon. To my right flowed what, for their size, seemed to be an equally mighty river of leafcutter ants hefting pink petals; to my left, a similar line of army ants carrying their slaughtered spiders. Looking from one species to the other, I recognized the apogees of two distinct lifestyles: the sedentary communities of vegetarian farmers and the migratory hordes of meat eaters.
How did leafcutters shift away from the hunter-gatherer habits of most other ants to a life of agriculture?1 Could they have encountered some of the same fortuitous circumstances that set human beings on the road to farming about ten millennia ago?2 When, for instance, early human hunter-gatherers harvested wild fruit and grain and then discarded or defecated seeds on waste heaps, these grew into a ready crop of fruiting plants. It might not have taken much skill for people to transform these useful “camp follower” species into sustainable gardens.
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